/* CSS Variables & Reset */
:root {
    --primary-bg: #0f0f23;
    --secondary-bg: #1a1a3e;
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(255, 255, 255, 0.1);
    --text-primary: #ffffff;
    --text-secondary: rgba(255, 255, 255, 0.7);
    --text-muted: rgba(255, 255, 255, 0.5);
    --accent-blue: #4f8cff;
    --accent-cyan: #00d4ff;
    --accent-purple: #a855f7;
    --accent-green: #10b981;
    --accent-orange: #f59e0b;
    --gradient-primary: linear-gradient(135deg, #4f8cff 0%, #a855f7 100%);
    --gradient-secondary: linear-gradient(135deg, #0f0f23 0%, #1a1a3e 50%, #2d1b4e 100%);
    --shadow-glow: 0 0 30px rgba(79, 140, 255, 0.3);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    background: var(--gradient-secondary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

.background-overlay {
    position: fixed; top: 0; left: 0; width: 100%; height: 100%; pointer-events: none; z-index: -1;
    background: radial-gradient(ellipse at 20% 20%, rgba(79, 140, 255, 0.15) 0%, transparent 50%),
                radial-gradient(ellipse at 80% 80%, rgba(168, 85, 247, 0.15) 0%, transparent 50%);
}

.container { max-width: 1400px; margin: 0 auto; padding: 0 20px; }
.section { padding: 80px 0; }
.section-title {
    font-size: 2.5rem; font-weight: 700; text-align: center; margin-bottom: 16px;
    background: var(--gradient-primary); -webkit-background-clip: text; -webkit-text-fill-color: transparent;
}
.section-subtitle { text-align: center; color: var(--text-secondary); font-size: 1.1rem; margin-bottom: 48px; }

/* Header */
.header {
    position: fixed; top: 0; left: 0; right: 0; z-index: 100; padding: 16px 0;
    background: rgba(15, 15, 35, 0.8); backdrop-filter: blur(20px); border-bottom: 1px solid var(--card-border);
}
.header .container { display: flex; justify-content: space-between; align-items: center; }
.logo { display: flex; align-items: center; gap: 12px; font-size: 1.25rem; font-weight: 600; }
.logo-icon { width: 40px; height: 40px; color: var(--accent-cyan); }
.nav { display: flex; gap: 32px; }
.nav a { color: var(--text-secondary); text-decoration: none; font-size: 0.95rem; transition: var(--transition); }
.nav a:hover { color: var(--text-primary); }

/* Calculator */
.calculator-section { padding-top: 120px; }
.calculator-grid { display: grid; grid-template-columns: 1fr 280px 1fr; gap: 24px; align-items: start; }
.calc-card {
    background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-lg);
    backdrop-filter: blur(20px); transition: var(--transition);
}
.calc-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-glow); }
.calc-card.ride-hailing .card-header { background: linear-gradient(135deg, rgba(79, 140, 255, 0.2) 0%, rgba(79, 140, 255, 0.05) 100%); }
.calc-card.self-drive .card-header { background: linear-gradient(135deg, rgba(16, 185, 129, 0.2) 0%, rgba(16, 185, 129, 0.05) 100%); }
.card-header { display: flex; align-items: center; gap: 16px; padding: 20px 24px; border-bottom: 1px solid var(--card-border); }
.card-icon { width: 48px; height: 48px; display: flex; align-items: center; justify-content: center; border-radius: var(--radius-md); background: rgba(255, 255, 255, 0.1); }
.card-icon svg { width: 28px; height: 28px; }
.ride-hailing .card-icon { color: var(--accent-blue); }
.self-drive .card-icon { color: var(--accent-green); }
.card-header h2 { font-size: 1.25rem; font-weight: 600; }
.card-body { padding: 24px; }
.group-title { font-size: 0.9rem; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; margin: 20px 0 12px; padding-bottom: 8px; border-bottom: 1px solid var(--card-border); }
.group-title:first-child { margin-top: 0; }
.input-group { margin-bottom: 16px; }
.input-group label { display: block; font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 6px; }
.input-group input {
    width: 100%; padding: 12px 16px; font-size: 1rem; color: var(--text-primary);
    background: rgba(255, 255, 255, 0.05); border: 1px solid var(--card-border); border-radius: var(--radius-sm);
    outline: none; transition: var(--transition);
}
.input-group input:focus { border-color: var(--accent-cyan); box-shadow: 0 0 0 3px rgba(0, 212, 255, 0.1); }
.card-result { padding: 20px 24px; background: rgba(0, 0, 0, 0.2); border-top: 1px solid var(--card-border); }
.result-item { display: flex; justify-content: space-between; align-items: center; padding: 8px 0; }
.result-label { color: var(--text-secondary); font-size: 0.95rem; }
.result-value { font-size: 1.1rem; font-weight: 600; font-family: 'SF Mono', monospace; }
.result-value.highlight { font-size: 1.4rem; background: var(--gradient-primary); -webkit-background-clip: text; -webkit-text-fill-color: transparent; }

/* Comparison Panel */
.comparison-panel {
    position: sticky; top: 100px; display: flex; flex-direction: column; align-items: center; gap: 24px;
    padding: 24px; background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-lg); backdrop-filter: blur(20px);
}
.vs-badge { width: 60px; height: 60px; display: flex; align-items: center; justify-content: center; font-size: 1.5rem; font-weight: 800; background: var(--gradient-primary); border-radius: 50%; box-shadow: var(--shadow-glow); }
.comparison-result { text-align: center; }
.winner { font-size: 1.25rem; font-weight: 700; margin-bottom: 8px; color: var(--accent-green); }
.savings { font-size: 1rem; color: var(--text-secondary); }
.comparison-chart { width: 100%; display: flex; flex-direction: column; gap: 16px; }
.chart-bar { display: flex; align-items: center; gap: 12px; }
.bar-label { width: 60px; font-size: 0.85rem; color: var(--text-secondary); text-align: right; }
.bar-fill { flex: 1; height: 24px; border-radius: 12px; transition: var(--transition); }
.chart-bar.ride .bar-fill { background: linear-gradient(90deg, var(--accent-blue), var(--accent-purple)); }
.chart-bar.drive .bar-fill { background: linear-gradient(90deg, var(--accent-green), var(--accent-cyan)); }
.bar-value { width: 80px; font-size: 0.9rem; font-weight: 600; font-family: 'SF Mono', monospace; }
.calculate-btn {
    display: flex; align-items: center; justify-content: center; gap: 8px; width: 100%; padding: 14px 24px;
    font-size: 1rem; font-weight: 600; color: var(--text-primary); background: var(--gradient-primary);
    border: none; border-radius: var(--radius-md); cursor: pointer; transition: var(--transition);
}
.calculate-btn svg { width: 20px; height: 20px; }
.calculate-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-glow); }

/* Formula Section */
.formula-section { background: rgba(0, 0, 0, 0.2); }
.formula-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 32px; }
.formula-card { background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-lg); padding: 32px; backdrop-filter: blur(20px); }
.formula-card h3 { font-size: 1.25rem; margin-bottom: 24px; color: var(--accent-cyan); }
.formula-block h4 { font-size: 0.9rem; color: var(--text-muted); margin: 20px 0 12px; text-transform: uppercase; }
.formula-block h4:first-child { margin-top: 0; }
.formula { padding: 12px 16px; margin-bottom: 8px; background: rgba(0, 0, 0, 0.3); border-radius: var(--radius-sm); border-left: 3px solid var(--accent-purple); }
.formula-text { font-family: 'SF Mono', Consolas, monospace; font-size: 0.95rem; color: var(--text-secondary); }
.formula-note { margin-top: 20px; padding: 16px; background: rgba(245, 158, 11, 0.1); border-radius: var(--radius-sm); border-left: 3px solid var(--accent-orange); }
.formula-note p { font-size: 0.9rem; color: var(--text-secondary); }

/* Examples Section */
.example-cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.example-card { background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-lg); overflow: hidden; backdrop-filter: blur(20px); transition: var(--transition); }
.example-card:hover { transform: translateY(-4px); }
.example-header { display: flex; align-items: center; gap: 12px; padding: 20px 24px; background: rgba(0, 0, 0, 0.2); border-bottom: 1px solid var(--card-border); }
.example-icon { font-size: 1.5rem; }
.example-header h3 { font-size: 1.1rem; font-weight: 600; }
.example-content { padding: 24px; }
.example-scenario { margin-bottom: 20px; }
.example-scenario h4, .example-calc h4 { font-size: 0.9rem; color: var(--accent-cyan); margin-bottom: 12px; }
.example-scenario ul { list-style: none; }
.example-scenario li { position: relative; padding-left: 20px; margin-bottom: 8px; color: var(--text-secondary); font-size: 0.95rem; }
.example-scenario li::before { content: '•'; position: absolute; left: 0; color: var(--accent-purple); }
.example-calc { margin-bottom: 16px; padding: 16px; background: rgba(0, 0, 0, 0.2); border-radius: var(--radius-sm); }
.example-calc p { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 6px; font-family: 'SF Mono', monospace; }
.example-calc strong { color: var(--accent-cyan); }
.example-result { padding: 16px; border-radius: var(--radius-sm); text-align: center; }
.example-result strong { display: block; font-size: 0.95rem; margin-bottom: 4px; }
.example-result.ride-wins { background: rgba(79, 140, 255, 0.15); border: 1px solid rgba(79, 140, 255, 0.3); color: var(--accent-blue); }
.example-result.drive-wins { background: rgba(16, 185, 129, 0.15); border: 1px solid rgba(16, 185, 129, 0.3); color: var(--accent-green); }
.example-result:not(.ride-wins):not(.drive-wins) { background: rgba(168, 85, 247, 0.15); border: 1px solid rgba(168, 85, 247, 0.3); color: var(--accent-purple); }
.result-note { font-size: 0.8rem !important; color: var(--text-muted) !important; }

/* Guide Section */
.guide-content { display: flex; flex-direction: column; gap: 32px; }
.guide-block { background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-lg); padding: 32px; backdrop-filter: blur(20px); }
.guide-block h3 { font-size: 1.25rem; margin-bottom: 24px; }
.guide-table { overflow-x: auto; }
.guide-table table { width: 100%; border-collapse: collapse; }
.guide-table th, .guide-table td { padding: 14px 16px; text-align: left; border-bottom: 1px solid var(--card-border); }
.guide-table th { font-size: 0.9rem; font-weight: 600; color: var(--text-muted); text-transform: uppercase; background: rgba(0, 0, 0, 0.2); }
.guide-table td { font-size: 0.95rem; color: var(--text-secondary); }
.guide-table tr:last-child td { border-bottom: none; }
.tips-list { display: flex; flex-direction: column; gap: 20px; }
.tip-item { display: flex; gap: 20px; padding: 20px; background: rgba(0, 0, 0, 0.2); border-radius: var(--radius-md); transition: var(--transition); }
.tip-item:hover { background: rgba(0, 0, 0, 0.3); }
.tip-number { width: 36px; height: 36px; display: flex; align-items: center; justify-content: center; font-size: 1rem; font-weight: 700; background: var(--gradient-primary); border-radius: 50%; flex-shrink: 0; }
.tip-content h4 { font-size: 1rem; margin-bottom: 8px; }
.tip-content p { font-size: 0.95rem; color: var(--text-secondary); line-height: 1.7; }

/* Ad & Footer */
.ad-container { margin: 40px auto; padding: 20px; background: var(--card-bg); border: 1px solid var(--card-border); border-radius: var(--radius-md); min-height: 100px; }
.footer { padding: 40px 0; text-align: center; border-top: 1px solid var(--card-border); }
.footer p { font-size: 0.9rem; color: var(--text-muted); margin-bottom: 16px; }
.footer-links { display: flex; justify-content: center; gap: 24px; }
.footer-links a { color: var(--text-secondary); text-decoration: none; font-size: 0.9rem; transition: var(--transition); }
.footer-links a:hover { color: var(--accent-cyan); }

/* Responsive */
@media (max-width: 1200px) {
    .calculator-grid { grid-template-columns: 1fr 1fr; }
    .comparison-panel { grid-column: 1 / -1; position: static; flex-direction: row; flex-wrap: wrap; justify-content: center; }
    .example-cards { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 900px) {
    .section-title { font-size: 2rem; }
    .calculator-grid { grid-template-columns: 1fr; }
    .formula-grid { grid-template-columns: 1fr; }
    .example-cards { grid-template-columns: 1fr; }
    .nav { display: none; }
}
@media (max-width: 600px) {
    .section { padding: 60px 0; }
    .section-title { font-size: 1.5rem; }
    .calculator-section { padding-top: 100px; }
    .tip-item { flex-direction: column; gap: 12px; }
}

/* Animations */
@keyframes fadeInUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
.calc-card, .formula-card, .example-card, .guide-block { animation: fadeInUp 0.6s ease forwards; }